Implantable stimulation devices are devices that generate and deliver electrical stimuli to body nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and deep brain stimulators to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder sublaxation, etc. The present invention may find applicability in all such applications, although the description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in U.S. Pat. No. 6,516,227.
Spinal cord stimulation is a well-accepted clinical method for reducing pain in certain populations of patients. As shown in FIGS. 1A and 1B, a SCS system typically includes an Implantable Pulse Generator (IPG) 100, which includes a biocompatible case 30 formed of titanium for example. The case 30 typically holds the circuitry and power source or battery necessary for the IPG to function, although IPGs can also be powered via external RF energy and without a battery. The IPG 100 is coupled to electrodes 106 via one or more electrode leads (two such leads 102 and 104 are shown), such that the electrodes 106 form an electrode array 110. The electrodes 106 are carried on a flexible body 108, which also houses the individual signal wires 112 and 114 coupled to each electrode. In the illustrated embodiment, there are eight electrodes on lead 102, labeled E1-E8, and eight electrodes on lead 104, labeled E9-E16, although the number of leads and electrodes is application specific and therefore can vary.
As shown in FIG. 2, the IPG 100 typically includes an electronic substrate assembly 14 including a printed circuit board (PCB) 16, along with various electronic components 20, such as microprocessors, integrated circuits, and capacitors mounted to the PCB 16. Two radiators are generally present in the IPG 100: a telemetry radiator 13 used to transmit/receive data to/from an external controller 12; and a charging radiator 18 for charging or recharging the IPG's power source or battery 26 using an external charger 50.
As just noted, an external controller 12, such as a hand-held programmer or a clinician's programmer, is used to wirelessly send data to and receive data from the IPG 100. For example, the external controller 12 can send programming data to the IPG 100 to dictate the therapy the IPG 100 will provide to the patient. Also, the external controller 12 can act as a receiver of data from the IPG 100, such as various data reporting on the IPG's status. The external controller 12, like the IPG 100, also contains a PCB 70 on which electronic components 72 are placed to control operation of the external controller 12. A user interface 74 similar to that used for a computer, cell phone, or other hand held electronic device, and including touchable buttons and a display for example, allows a patient or clinician to operate the external controller 12. The communication of data to and from the external controller 12 is enabled by a radiator, which may comprise for example an antenna or (as shown) a radiator 17, which is discussed further below.
The external charger 50, also typically a hand-held device, is used to wirelessly convey power to the IPG 100, which power can be used to recharge the IPG's battery 26. The transfer of power from the external charger 50 is enabled by a radiator which can comprise a radiator 17′, which is discussed further below. For the purpose of the basic explanation here, the external charger 50 is depicted as having a similar construction to the external controller 12, but in reality they will differ in accordance with their functionalities as one skilled in the art will appreciate.
Wireless data telemetry and power transfer between the external devices 12 and 50 and the IPG 100 takes place via inductive coupling, and specifically magnetic inductive coupling. To implement such functionality, and as alluded to above, both the IPG 100 and the external devices 12 and 50 have radiators which act together as a pair. In case of the external controller 12, the relevant pair of radiators comprises radiator 17 from the controller and radiator 13 from the IPG. While in case of the external charger 50, the relevant pair of radiators comprises radiator 17′ from the external charger and radiator 18 from the IPG.
When data is to be sent from the external controller 12 to the IPG 100 for example, radiator 17 is energized with an alternating current (AC). Such energizing of the radiator 17 to transfer data can occur using a Frequency Shift Keying (FSK) protocol for example, such as disclosed in U.S. patent application Ser. No. 11/780,369, filed Jul. 19, 2007. Energizing the radiator 17 produces an magnetic field, which in turn induces a current in the IPG's radiator 13, which current can then be demodulated to recover the original data.
When power is to be transmitted from the external charger 50 to the IPG 100, radiator 17′ is again energized with an alternating current. Such energizing is generally of a constant frequency, and may be of a larger magnitude than that used during the transfer of data, but otherwise the physics involved are similar.
Energy to energize radiators 17 and 17′ can come from batteries in the external controller 12 and the external charger 50, respectively, which like the IPG's battery 26 are preferably rechargeable. However, power may also come from plugging the external controller 12 or external charger 50 into a wall outlet plug (not shown), etc.
As is well known, inductive transmission of data or power can occur transcutaneously, i.e., through the patient's tissue 25, making it particularly useful in a medical implantable device system. During the transmission of data or power, the radiators 17 and 13, or 17′ and 18, preferably lie in planes that are parallel, along collinear axes, and with the radiators in as close as possible to each other. Such an orientation between the radiators 17 and 13 will generally improve the coupling between them, but deviation from ideal orientations can still result in suitably reliable data or power transfer.
The Inventors consider it unfortunate that the typical implantable medical device system requires two external devices: the external controller 12 and the external charger 50. Both are needed by a typical patient at one time or another with good frequency. The external charger 50 is typically needed to recharge the battery 26 in the IPG 100 on a regular basis, as often as every day depending on the stimulation settings. The external controller 12 can also be needed on a daily basis by the patient to adjust the stimulation therapy as needed at a particular time. Therefore, the patient is encumbered by the need to manipulate two completely independent devices. This means the patient must: learn how to use both devices; carry the bulk of both devices (e.g., when traveling); replace the batteries in both devices and/or recharge them as necessary; pay for both devices, etc. In all, the requirement of two independent external devices is considered inconvenient.
This disclosure provides embodiments of solutions to mitigate these problems.